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[Kieran]

Hello have had problems with hot starting recently and now i think i have a fault code P0173. The car is the 2.6 estate 2001. Does anyone know what this code may relate to.

Cheers

[rickyboy]

Fault code is Heated Exhaust Gas Oxygen (HEGO) sensor.  Have you any holes in your exhaust - that would bring this code up?  Because your car has trouble starting hot then it could be the sensor itself.  

Wait around for some more answers as quite a lot of things can bring this code up.  There will be some experts along shortly!

[Kieran]

Thanks for your reply no holes in the exhaust so could it be the crank sensor.

cheers

[rickyboy]

Unlikely to be the crank sensor far more likely to be the o2 sensor (if it's a sensor problem at all).  It could be the cats getting tired or the fuel mixture is wrong.  Best to test the o2 sensor is working with a voltmeter and go from there.  

[Kieran]

Thanks but why is it having trouble starting when hot. New battery, car running nice, but hot starting is a problem. Someone said earlier that it could be the crank sensor as they do tend to go at around 100000 miles and mine has passed that. Surely a fault code would appear for the sensor.
Cheers

[rickyboy]

Usually you'll find the dreaded crank sensor will bring up a fault code if it is faulty.  The crank sensor is known for causing starting problems but if you're getting a HEGO code I would expect it to relate with this.  Try reading the codes again - someone on the forum has discovered you can read codes on your model yourself.  

Press the accelerator and brake pedals to the floor with the ignition off.  Then turn the ignition on to position 2 (don't start the car).  Count the flashes from the EML and report them back.

[kcl]

The code 0173 is the same I have had without any reasonable explanation, I also had the P0170 for the other bank. Seems to me that its the pre-cats that cause this, same thing as most of the 3,2 owners here have but with different codes. Local Opel-shop was/is unable to help me with this, they suggested it to be MAF but it was not... I'd not be worried.

For the starting problems I have no idea, but might be worthwhile to change the crank sensor since it's no tthat expensive

[Kieran]

Thanks i will change the crank sensor because of its mileage and problem starting, hope it dosen't prove to problematic. I did have the emissons light come on not so long ago and although i took it to a garage three times they where still unable to resolve the problem,ended up giving my money back, took the light bulb out and that solved it

Cheers

[martbax]

I had a problem with eml light and codes P0173 and p0170. VX changed a split vacuum pipe which needed doing but did not solve the problem. The two codes related to fuel trim malfunction on banks 1 and 2. When VX gave up I researched my own solution.

When the car is cold it is running in open loop mode. This means that it takes information from the airflow meter (amongst others) and injects the correct amount of fuel to match the air according to its engine map. When the engine warms up it goes into closed loop mode in which the front oxygen sensors test the mixture. If this mixture is incorrect it adjusts the short term fuel trim and also adjusts the long term fuel trim to take account of wear and tear. When it runs out of long term fuel trim adjustment it triggers the codes and the eml.
In my case the long term fuel trim was + 25%. This means that the mixture was far too weak and it was pumping in extra fuel in closed loop mode to try and compensate. This could be caused by
a) a massive air leak
b) the car underestinating the amount of air that was going in.

I used a cheap tech 2 to check the measured air flow and found that it was less than half of what was expected from a scorpio 2.9 which was the only car I could get a figure for (and which I expected to be similar to my 3.2).

The air flow meter contains sensor wires. I removed it and tried cleaning the wires but that had no effect. I bought a Bosch airflow meter on the net for £130 ( compared with VX about £250) and changed it. Immediately the long term fuel trim went down to zero on both banks and the airflow doubled. The eml has stayed off since.

I think that if your car has run out of the ability to enrich the fuel because your sensor is very dirty you could be getting a weak mixture which would give you difficult starting and running although I would expect this to give cold start problems as well.

[Kieran]

What a reply excellent.Yes the emission light could not be fixed and you may have come up with the solution. But as far as the starting,brillant from cold only very difficult after towing when the engine is warm.Once it has cooled down no problems.
Thanks for yor reply